In the course of testing and preparing subterranean oil and gas wells for production, a well packer is run into the well on a work string or production tubing. The packer is used: (a) to support the production tubing and the other completion equipment such as filter screens adjacent to a producing formation, and (b) to seal the annulus between the outside of the production tubing and the inside of the well casing, thus blocking movement of fluids through the annulus past the packer location. The packer is equipped with anchor slips that have opposed camming surfaces that cooperate with complementary opposed wedging surfaces. The anchor slips are radially extendable into gripping engagement against the well casing bore in response to relative axial movement of the wedging surfaces. The packer also carries annular seal elements that are expandable radially into sealing engagement against the bore of the well casing in response to axial compression forces. Hydraulic or mechanical means may be used to set the anchor slips and the sealing elements.
After the packer has been set and sealed against the well casing bore, it is designed to maintain the seal after the hydraulic or mechanical setting force is removed. It is absolutely essential that the packer remain locked in its set and sealed configuration while withstanding hydraulic pressures that may be applied from the formation and/or the manipulation of the tubing string and service tools. In deep wells this may be much more difficult as the packer and its components are subjected to downhole temperatures as high as 600.degree. F., and downhole pressures of up to 10,000 psi. Moreover, the packer should be able to withstand the application of external hydraulic pressures at levels up to as much as 10,000 psi in either direction, and still be retrievable after exposure for periods of 10 to 15 years or more. After such long periods of extended service under extreme pressure and temperature conditions, it is desirable that the packer be retrievable from the well. Appropriate manipulation of the tubing string must cause the packer to be released and unsealed from the well bore, with the anchor slips and seal elements being retracted sufficiently to avoid seizure against well bore restrictions that are smaller than the retracted seal assembly, for example, at a makeup union, collar union, nipple, etc.
Currently, permanent and retrievable packers are used for long-term placement in high temperature, high pressure wells. While so-called permanent packers exist, most are still designed to be retrievable through some form of manipulation to release the packer elements and anchor slips, with the packer then to be removed from the well bore. However, since the packers are threaded into the production tubing and are held in firm contact with the well casing, the problem of how to retrieve them occurs. Conventionally, retrievable packers have been removed from the well by first removing all of the production tubing from a threaded joint at the top of the packer to be removed. Then, a new work string with a releasing tool attached is introduced into the well. The releasing tool attaches to the threaded coupling on the top of the packer and operates the release mechanism of the packer. The packer is then retrieved by a tensile force applied to the work string transferred to the packer at the threaded coupling. However, the extra operation of removing the production tubing from above the packer before the packer can be released and retrieved is expensive in time and manpower to accomplish.
Therefore, what is needed in the art is a slick line packer release system that simplifies the locating, release and retrieval of a set packer without removing the production tubing.